local _VERSION = "0.2.0"

local args = table.pack(...)
local command = args[1]

local GOO_BLOCK_PREFIX = "justdirethings:gooblock_tier"
local MIN_START_FUEL = 50
local REFUEL_THRESHOLD = 1000
local WAIT_SECONDS = 2

local FUEL_ITEMS = {
	"justdirethings:coal_t4",
	"justdirethings:coal_t3",
	"justdirethings:coal_t2",
	"justdirethings:coal_t1",
	"minecraft:coal",
}

local PROCESS_ITEMS = {
	["minecraft:iron_block"] = { tier = 1, label = "iron" },
	["minecraft:coal_block"] = { tier = 1, label = "coal" },
	["mekanism:block_charcoal"] = { tier = 1, label = "charcoal" },
	["minecraft:gold_block"] = { tier = 2, label = "gold" },
	["minecraft:diamond_block"] = { tier = 3, label = "diamond" },
	["minecraft:netherite_block"] = { tier = 4, label = "netherite" },
}

local FEEDING_ITEMS_BY_TIER = {
	[1] = { "minecraft:sugar", "minecraft:rotten_flesh" },
	[2] = { "minecraft:nether_wart" },
	[3] = { "minecraft:chorus_fruit" },
	[4] = { "minecraft:sculk" },
}

local loggedBlockedItems = {}

local function isFlag(name)
	return function(arg)
		return arg == "-" .. name or arg == "--" .. name
	end
end

local isHelpFlag = isFlag("help")
local isVersionFlag = isFlag("version")

local function printUsage()
	print("goo usage:")
	print()
	print("\t\t\tgoo start")
	print("\t\t\tgoo version")
	print("\t\t\tgoo help")
end

if command == "version" or isVersionFlag(command) then
	print("goo v" .. _VERSION)
	return
end

if command == nil or command == "" or command == "help" or isHelpFlag(command) then
	printUsage()
	return
end

if command ~= "start" then
	printUsage()
	return
end

if not turtle then
	error("goo must be run on a turtle")
end

local function hasPickaxeEquipped()
	local left = turtle.getEquippedLeft()
	local right = turtle.getEquippedRight()

	return (left and string.match(left.name or "", "_pickaxe$") ~= nil)
		or (right and string.match(right.name or "", "_pickaxe$") ~= nil)
end

local function turnAround()
	turtle.turnRight()
	turtle.turnRight()
end

local function parseGooTier(blockName)
	local tier = string.match(blockName or "", "^" .. GOO_BLOCK_PREFIX .. "(%d+)$")

	return tonumber(tier)
end

local function isGooBlock(blockName)
	return parseGooTier(blockName) ~= nil
end

local function isProcessBlock(blockName)
	return PROCESS_ITEMS[blockName] ~= nil
end

local function inspectGoo()
	local ok, inspected = turtle.inspectUp()

	if not ok then
		error("expected a Just Dire Things goo block above the turtle")
	end

	local tier = parseGooTier(inspected.name)

	if not tier then
		error("expected a Just Dire Things goo block above the turtle, got " .. tostring(inspected.name))
	end

	return tier, inspected
end

local function findItemSlot(itemName)
	for slot = 1, 16 do
		local item = turtle.getItemDetail(slot)

		if item and item.name == itemName then
			return slot, item
		end
	end

	return nil
end

local function waitForInventory(message)
	if message then
		print(message)
	end

	os.pullEvent("turtle_inventory")
end

local function hasFreeSlot()
	for slot = 1, 16 do
		if turtle.getItemCount(slot) == 0 then
			return true
		end
	end

	return false
end

local function ensureMiningSpace()
	while not hasFreeSlot() do
		waitForInventory("Inventory is full. Remove items to keep mining.")
	end
end

local function getFuelLevel()
	local fuelLevel = turtle.getFuelLevel()

	if fuelLevel == "unlimited" then
		return nil
	end

	return fuelLevel
end

local function getRefuelTarget()
	local fuelLimit = turtle.getFuelLimit()

	if fuelLimit == "unlimited" or fuelLimit >= REFUEL_THRESHOLD then
		return REFUEL_THRESHOLD
	end

	return fuelLimit
end

local function findFuelSlot()
	for i = 1, #FUEL_ITEMS do
		local slot, item = findItemSlot(FUEL_ITEMS[i])

		if slot then
			return slot, item
		end
	end

	return nil
end

local function refuelFromInventory()
	local fuelLevel = getFuelLevel()

	if not fuelLevel or fuelLevel >= getRefuelTarget() then
		return false
	end

	local previousSlot = turtle.getSelectedSlot()
	local consumedFuel = false

	while fuelLevel < getRefuelTarget() do
		local slot, item = findFuelSlot()

		if not slot then
			break
		end

		turtle.select(slot)

		if turtle.refuel(1) then
			consumedFuel = true
			print("Refueled with " .. item.name .. ". Fuel: " .. tostring(turtle.getFuelLevel()))
			fuelLevel = getFuelLevel()
		else
			print("Could not refuel with " .. item.name .. ".")
			break
		end
	end

	turtle.select(previousSlot)

	return consumedFuel
end

local function ensureStartFuel()
	while true do
		local fuelLevel = getFuelLevel()

		if not fuelLevel or fuelLevel >= MIN_START_FUEL then
			return
		end

		refuelFromInventory()
		fuelLevel = getFuelLevel()

		if not fuelLevel or fuelLevel >= MIN_START_FUEL then
			return
		end

		waitForInventory("Fuel is below " .. tostring(MIN_START_FUEL) .. ". Insert fuel to start.")
	end
end

local function ensureRuntimeFuel()
	local fuelLevel = getFuelLevel()

	if not fuelLevel then
		return
	end

	if fuelLevel < getRefuelTarget() then
		refuelFromInventory()
	end

	fuelLevel = getFuelLevel()

	while fuelLevel and fuelLevel < MIN_START_FUEL do
		waitForInventory("Fuel is below " .. tostring(MIN_START_FUEL) .. ". Insert fuel to continue.")
		refuelFromInventory()
		fuelLevel = getFuelLevel()
	end
end

local function findFeedingSlot(gooTier)
	local feedingItems = FEEDING_ITEMS_BY_TIER[gooTier] or {}

	for i = 1, #feedingItems do
		local slot, item = findItemSlot(feedingItems[i])

		if slot then
			return slot, item
		end
	end

	return nil
end

local function findEligibleProcessSlot(gooTier)
	for slot = 1, 16 do
		local item = turtle.getItemDetail(slot)
		local processItem = item and PROCESS_ITEMS[item.name]

		if processItem then
			if processItem.tier <= gooTier then
				return slot, item, processItem
			end

			local logKey = item.name .. ":" .. tostring(gooTier)

			if not loggedBlockedItems[logKey] then
				print(
					item.name
						.. " requires goo tier "
						.. tostring(processItem.tier)
						.. ", current tier is "
						.. tostring(gooTier)
				)
				loggedBlockedItems[logKey] = true
			end
		end
	end

	return nil
end

local function ensureGooAlive()
	while true do
		local gooTier, inspected = inspectGoo()

		if inspected.state and inspected.state.alive == true then
			return gooTier
		end

		local slot, item = findFeedingSlot(gooTier)

		if not slot then
			waitForInventory("Goo tier " .. tostring(gooTier) .. " is not alive. Waiting for feeding item...")
		else
			turtle.select(slot)
			print("Goo tier " .. tostring(gooTier) .. " is not alive. Feeding with " .. item.name .. "...")

			if not turtle.placeUp() then
				print("Could not feed the goo. Waiting before retry...")
				os.sleep(WAIT_SECONDS)
			else
				os.sleep(1)
			end
		end
	end
end

local function selectProcessItem(gooTier)
	local slot, item, processItem = findEligibleProcessSlot(gooTier)

	if not slot then
		return nil
	end

	turtle.select(slot)

	return item, processItem
end

local function workTarget(inspectFn, digFn, placeFn, gooTier, targetName)
	local ok, inspected = inspectFn()

	if ok then
		if isGooBlock(inspected.name) then
			return false
		end

		if isProcessBlock(inspected.name) then
			return false
		end

		print("Mining processed " .. targetName .. " block: " .. tostring(inspected.name))
		ensureMiningSpace()
		return digFn()
	end

	local item = selectProcessItem(gooTier)

	if not item then
		return false
	end

	print("Placing " .. item.name .. " on goo " .. targetName)
	return placeFn()
end

local function workHorizontalSide(gooTier, sideIndex)
	if not turtle.forward() then
		print("Cannot move to horizontal side " .. tostring(sideIndex) .. ". Waiting...")
		return false
	end

	local changed = workTarget(turtle.inspectUp, turtle.digUp, turtle.placeUp, gooTier, "side")

	if not turtle.back() then
		error("could not return below the goo")
	end

	return changed
end

local function workHorizontalSides(gooTier)
	local changed = false

	for sideIndex = 1, 4 do
		changed = workHorizontalSide(gooTier, sideIndex) or changed
		turtle.turnRight()
	end

	return changed
end

-- Returns `changed, reachedTop`. `reachedTop` is true only once we have actually
-- climbed above the goo and inspected its top face, so the caller can stop trying
-- the remaining sides; it stays false when this side is blocked or unclimbable.
local function workTopFromCurrentSide(gooTier)
	if not turtle.forward() then
		return false, false
	end

	-- Only the presence of a block above matters here; ignore the inspect metadata.
	local sideOccupied = turtle.inspectUp()
	local changed = false
	local reachedTop = false

	if not sideOccupied then
		if turtle.up() then
			if turtle.up() then
				turnAround()
				changed = workTarget(turtle.inspect, turtle.dig, turtle.place, gooTier, "top")
				reachedTop = true
				turnAround()

				if not turtle.down() then
					error("could not descend from top placement position")
				end
			else
				print("Cannot climb high enough to work on the top side.")
			end

			if not turtle.down() then
				error("could not return to side floor position")
			end
		else
			print("Cannot climb to work on the top side.")
		end
	end

	if not turtle.back() then
		error("could not return below the goo after top side check")
	end

	return changed, reachedTop
end

local function workTop(gooTier)
	local changed = false
	local done = false

	-- Iterate all four sides so the four turnRight calls net to zero (facing is
	-- restored), but skip the climb once the single top face has been handled.
	for _ = 1, 4 do
		if not done then
			local sideChanged, reachedTop = workTopFromCurrentSide(gooTier)
			changed = sideChanged or changed
			done = sideChanged or reachedTop
		end

		turtle.turnRight()
	end

	return changed
end

local function turnLeft(times)
	for _ = 1, times do
		turtle.turnLeft()
	end
end

local function moveToSideFacingCenter()
	for turns = 0, 3 do
		if turtle.forward() then
			turnAround()
			return turns
		end

		turtle.turnRight()
	end

	return nil
end

local function returnFromBottomSide(turns)
	if not turtle.forward() then
		return false
	end

	turnAround()
	turnLeft(turns)

	return true
end

local function workBottom()
	local gooTier = ensureGooAlive()

	local turns = moveToSideFacingCenter()

	if not turns then
		print("Cannot move to a side position for bottom placement. Waiting...")
		return false
	end

	local changed = false

	-- The bottom face is worked as one atomic round-trip (place -> wait -> mine ->
	-- return) rather than fire-and-forget like the other faces, because the turtle
	-- must vacate and then reclaim its home cell within a single pass.
	while true do
		local ok, inspected = turtle.inspect()

		if not ok then
			if changed then
				if returnFromBottomSide(turns) then
					return changed
				end

				print("Center position is clear, but the turtle could not return. Waiting...")
				os.sleep(WAIT_SECONDS)
			else
				local item = selectProcessItem(gooTier)

				if item then
					print("Placing " .. item.name .. " on goo bottom")

					if turtle.place() then
						changed = true
					else
						print("Could not place bottom block.")
					end
				elseif returnFromBottomSide(turns) then
					return changed
				else
					print("Center position is blocked. Waiting...")
					os.sleep(WAIT_SECONDS)
				end
			end
		elseif isProcessBlock(inspected.name) then
			print("Bottom block is still processing. Waiting outside...")
			os.sleep(WAIT_SECONDS)
		elseif isGooBlock(inspected.name) then
			error("unexpected goo block in the turtle center position")
		else
			print("Mining processed bottom block: " .. tostring(inspected.name))
			ensureMiningSpace()

			if turtle.dig() then
				changed = true
			else
				print("Could not mine bottom block. Waiting...")
				os.sleep(WAIT_SECONDS)
			end
		end
	end
end

print("goo started. Place the turtle directly below the goo block.")

if not hasPickaxeEquipped() then
	error("goo requires a turtle with a pickaxe equipped")
end

ensureStartFuel()

while true do
	ensureRuntimeFuel()

	local gooTier = ensureGooAlive()
	-- Also relied on for its side effect: emits the "requires goo tier X" warnings
	-- for blocks the current tier cannot process yet.
	local hasEligibleBlocks = findEligibleProcessSlot(gooTier) ~= nil

	local changed = false

	changed = workTop(gooTier) or changed
	changed = workHorizontalSides(gooTier) or changed
	changed = workBottom() or changed

	if not changed then
		if hasEligibleBlocks then
			print("No free goo side found. Waiting for processing...")
			os.sleep(WAIT_SECONDS)
		else
			waitForInventory("No eligible process block found. Waiting for inventory...")
		end
	end
end